The officer, Stephen O'Sullivan, from Co Clare, is the fourth garda to die using an officially-issued weapon in just over two years.

He was stationed in Cashel, Co Tipperary, and was buried yesterday near his home outside Ennis. He had six years service in the force.

He is understood to have taken his handgun home and shot himself late on Wednesday night and no external issues concerning the force are suspected.

In July last year, 53-year-old retired detective garda Peter O'Donnell took an Uzi sub-machine gun from a locker in Carrick-on-Shannon Garda Station and shot himself. Det Garda O'Donnell had served for 35 years and frequently visited his friends in the station.

In April 2008, a 48-year-old detective garda, Paul Gilton, shot himself in an office in the Dublin Metropolitan Headquarters at Harcourt Square. His inquest heard that he had been socialising with colleagues earlier in the day and had returned alone to his office, where he took his own life with his official handgun. He had earlier sent texts and voice messages to the mobile phone of an ex-girlfriend.

Garda Joseph O'Keeffe, 48, shot himself in the public office of Enniscorthy Garda Station, Co Wexford, in July 2008. He had been receiving psychiatric care and had been staying in living quarters at Oulart Garda Station outside Enniscorthy. He was married with a grown family.

Part of any investigation into the latest death will concern whether or not there was any work-related stress that might have contributed to the death. Sources said yesterday that there appeared to be no work-related problems but possible personal ones.

One of the issues the Ombudsman has looked at in recent years has been the issue of bullying. Gardai say they can identify at least two cases of young gardai taking their lives due to work pressure.

Disciplinary pressure within the force is a cause of considerable amounts of stress-related leave, gardai say.